I've got the following problem with 7th and 8th GPU on my motherboard:

I had 6 GPU (5x 1080ti and 1x 1070) on my ASROCK Z370 Killer SLI motherboard, 2 power sources 1200W.
All drivers are updated for motherboard, GPUs, I also use onboard graphics card as I have plugged in LCD to it.

Few weeks ago, I found out that I can use M.2 slots as PCIe slot so I bought additional 1080ti.
So, I bought M.2 to PCIe adapter and plugged 7th GPU into this.
However, I've got unstable mining when I add 7th GPU, actually I was able to use only 1 M.2 on this motherboard.
I was even forced to use 1070 card on M.2 port because it seems that 1080ti was not recognized.
Well, bios does not detect M.2 device at all .
Recently, I decided that I update BIOS to 1.1 version that was successful but still unstable mining.


Unstable mining means I get blue screen on Windows 10 with some VIDEO related problem (I do not remember error message)

What is your experience with GPU  in M.2 port on your motherboard?

Could it be that 4 1080ti GPUs is too much for 1200W power source?

Thanks for experience.